Method and system for a linearized transmitter including a power amplifier

ABSTRACT

Various aspect of a system for a linearized transmitter including a power amplifier may include at least one transconductance amplifier that enables generation of a single analog quadrature signal. Transmitter mixers may enable generation of a plurality of upconverted RF signals in a corresponding plurality of RF processing chains based on the generated single analog quadrature signal. In various embodiments of the invention, a gain stage, for example gain stage, may also be referred to as an RF processing chain. Power amplifier circuit may enable generation of a corresponding plurality of RF output signals within a wireless communication system based on the generated plurality of upconverted RF signals.

CROSS-REFERENCE TO RELATED APPLICATIONS/INCORPORATION BY REFERENCE

This application makes reference to, claims priority to, and claims thebenefit of U.S. Provisional Application Ser. No. 60/868,818, filed onDec. 6, 2006.

This application makes reference to U.S. patent application Ser. No.11/618,876, filed on Dec. 31, 2006.

Each of the above stated applications is hereby incorporated herein byreference in its entirety.

FIELD OF THE INVENTION

Certain embodiments of the invention relate to wireless communications.More specifically, certain embodiments of the invention relate to amethod and system for a linearized transmitter including a poweramplifier.

BACKGROUND OF THE INVENTION

Power amplifier (PA) circuits, which are utilized in wireless local areanetwork (WLAN) systems, may be required to operate over a wide range offrequencies. Throughout most of the world, WLAN systems operate in theindustrial scientific and industrial (ISM), and/or unlicensed nationalinformation infrastructure (U-NII) frequency bands. The ISM bandcomprises 2.4-2.4835 GHz and 5.725-5.85 GHz frequency ranges, while theU-NII band comprises 5.15-5.25 GHz, 5.25-5.35 GHz and 5.725-5.825 GHzfrequency ranges. The IEEE has adopted a series of resolutions 802.11,which specify allowable frequency bands for use in WLAN systems anddevices. The IEEE 802.11 resolutions define a 2.4 GHz frequency band,and a 5 GHz frequency band. The 2.4 GHz frequency band comprises the2.4-2.4835 GHz portion of the ISM band. The 5 GHz frequency bandcomprises the U-NII frequency band. IEEE 802.11b and IEEE 802.11gcomprise specifications for the operation of WLAN systems and devicesfor the 2.4 GHz frequency band, while IEEE 802.11a comprisesspecifications for the operation of WLAN systems and devices for the 5GHz frequency band.

A PA circuit in a wireless system is typically a large signal device. InWLAN systems, the PA circuit may transmit output signals at averagepower levels in the range of 10 dBm to 15 dBm, and peak power levels ofabout 25 dBm, for example. In WLAN systems, which use OFDM or CCKmodulation, output power levels may vary widely such that the ratio ofthe peak power level to the average power level may be large, forexample, 12 dB for OFDM and 6 dB for CCK. Because of these large swingsin output power levels, PA circuits may distort the output signal.Distortion, however, is a characteristic, which may be observed in PAcircuits that are utilized across a wide range of applications, and maynot be limited to PA circuits utilized in wireless systems. There aretwo metrics, which may be utilized to evaluate the distortionperformance of PA circuits. These metrics may be referred to asamplitude modulation to amplitude modulation (AM-AM) distortion, andamplitude modulation to phase modulation (AM-PM) distortion.

The AM-AM distortion provides a measure of the output power level,p_(out), in response to the input power level, p_(in). The input powerlevel, and output power level are each typically measured in units ofdBm, for example. In an ideal, non-distorting, PA circuit, the outputpower level changes linearly in response to a change in the input powerlevel. Thus, for each Δp_(in) change in the input power level there maybe a corresponding change in the output power level Δp_(out). The AM-AMdistortion may be observed when, for example, the output power level inresponse to a first input power level may be p_(out1)≈αp_(in1), wherethe output level in response to a second input power level may bep_(out2)≈βp_(in2), when α≠β.

The AM-PM distortion provides a measure of the phase of the outputsignal in relation to the input signal (or output phase) in response tothe input power level. Output phase is typically measured in units ofangular degrees. The AM-PM distortion may be observed when, for example,the output phase changes in response to a change in input power level.

Limitations in the performance of PA circuitry due to distortion may beexacerbated when the PA is integrated in a single integrated circuit(IC) device with other radio frequency (RF) transmitter circuitry [suchas digital to analog converters (DAC), low pass filters (LPF), mixers,and RF programmable gain amplifiers (RFPGA)]. Whereas the pressing needto increase the integration of functions performed within a single IC,and attendant increase in the number of semiconductor devices, may pushsemiconductor fabrication technologies toward increasingly shrinkingsemiconductor device geometries, these very semiconductor fabricationtechnologies may impose limitations on the performance of the integratedPA circuitry. For example, utilizing a 65 nm CMOS process may restrictthe range of input power levels for which the PA provides linear outputpower level amplification.

The AM-AM distortion and/or the AM-PM distortion comprise transmitterimpairments that may result in signal transmission errors that mayresult in unintentional and/or undesirable modifications in themagnitude and/or phase of transmitted signals. When transmittingquadrature RF signals, the AM-AM distortion and/or the AM-PM distortionmay cause unintentional and/or undesirable modifications in themagnitude and/or phase of the I components and/or Q components in thetransmitted signals.

The transmission of erroneous signals from an RF transmitter may resultin erroneous detection of data contained within the received signals atan RF receiver. The result may be reduced communications quality asmeasured, for example, by packet error rate (PER), and/or bit error rate(BER).

Communications standards may specify a limit for Error Vector Magnitude(EVM) in a transmitted signal. For example, IEEE 802.11g standard forWLAN communications specifies that EVM_(dB) for a 54 Mbps transmittedsignal may be no greater than −25 dB. Thus, some conventional RFtransmitters may be required to limit the peak power level for signalsgenerated by the PA to ensure that the transmitted signals comply withEVM specifications. One potential limitation imposed by the reducedoutput power level is the reduced operating range in wirelesscommunications. In this regard, the EVM specification may reduce theallowable distance between a transmitting antenna and a receivingantenna for which signals may be transmitted from an RF transmitter andreceived by an RF receiver, in relation to the operating range thatwould be theoretically possible if the RF transmitter were able totransmit signals at the maximum, or saturation, output power level thatcould be generated by the PA.

Further limitations and disadvantages of conventional and traditionalapproaches will become apparent to one of skill in the art, throughcomparison of such systems with some aspects of the present invention asset forth in the remainder of the present application with reference tothe drawings.

BRIEF SUMMARY OF THE INVENTION

A method and system for a linearized transmitter including a poweramplifier, substantially as shown in and/or described in connection withat least one of the figures, as set forth more completely in the claims.

These and other advantages, aspects and novel features of the presentinvention, as well as details of an illustrated embodiment thereof, willbe more fully understood from the following description and drawings.

BRIEF DESCRIPTION OF SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 is a block diagram illustrating and exemplary multiband mobileterminal, which may be utilized in connection with an embodiment of theinvention.

FIG. 2 is a block diagram of an exemplary multiband RF transmitter, inaccordance with an embodiment of the invention.

FIG. 3 is an exemplary block diagram illustrating a single chip RFtransmitter and receiver utilizing feedback of the RF output from thetransmitter through the receiver, in accordance with an embodiment ofthe invention.

FIG. 4 is a flowchart illustrating exemplary steps for generating aplurality of output RF signals in a multiband RF transmitter, inaccordance with an embodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION

Certain embodiments of the invention may be found in a method and systemfor a linearized transmitter including a power amplifier. Variousembodiments of the invention may comprise a multiband RF transmitterthat receives a digital baseband signal. The received digital basebandsignal may be subsequently converted to an analog representation andfiltered to generate a quadrature signal. The multiband RF transmittermay then utilize the single quadrature signal to generate a plurality ofRF output signals, where each of the RF output signals comprises afrequency selected from distinct frequency bands. In an exemplarymultiband RF transmitter utilized in an WLAN system, one of theplurality of RF output signals may comprise a frequency selected fromthe 2.4 GHz frequency band, while a second one of the plurality of RFoutput signals may comprise a frequency selected from the 5 GHzfrequency band.

In some conventional systems, multiple RF output signals from distinctfrequency bands may be generated by a corresponding plurality oftransmitter chains, where each of the transmitter chains may comprisecircuitry the receives a digital baseband signal and generates a singleanalog RF output signal among the plurality of RF output signals.

Various embodiments of the invention may comprise a demarcation point,which may divide the transmitter chain into a transconductance stage anda gain stage. The transconductance stage may receive a single digitalbaseband signal and generate a single analog quadrature signal. The gainstage may receive a single quadrature signal and generate a single RFoutput signal. In various embodiments of the invention, a multiband RFtransmitter may generate a plurality of RF output signals by utilizing asingle transconductance stage, and a plurality of gain stages, where thenumber of gain stages may be equal to the number of RF output signals.In such various embodiments of the invention, the quadrature signaloutput from the transconductance stage may be input to each of the gainstages. Each gain stage may then generate a corresponding one of theplurality of RF output signals.

FIG. 1 is a block diagram illustrating and exemplary multiband mobileterminal, which may be utilized in connection with an embodiment of theinvention. Referring to FIG. 1, there is shown mobile terminal 120 and aplurality of antennas 121 a and 121 b. The mobile terminal 120 maycomprise a multiband RF transceiver 122, a digital baseband processor129, a processor 125, a memory 127, and a plurality of switches 124 aand 124 b. The multiband RF transceiver 122 may comprise a multiband RFreceiver 123 a, and a multiband RF transmitter 123 b. The antenna 121 amay enable the transmission and/or reception of signals within one of aplurality of RF frequency ranges. The antenna 121 b may enable thetransmission and/or reception of signals within a distinct one of theplurality of RF frequency ranges. The transmit and receive antenna 121 amay be communicatively coupled to the multiband RF receiver 123 a andthe multiband RF transmitter 123 b via the switch 124 a. The transmitand receive antenna 121 b may be communicatively coupled to themultiband RF receiver 123 a and the multiband RF transmitter 123 b viathe switch 124 b. The switch 124 a may be utilized to switch the antenna121 a between transmit and receive functions. The switch 124 b may beutilized to switch the antenna 121 b between transmit and receivefunctions.

The multiband RF transmitter 123 b may comprise suitable logic,circuitry, and/or code that may enable processing of one or more RFsignals for transmission. A plurality of RF signals may be transmitted,each within a distinct frequency range. The multiband RF transmitter 123b may enable transmission of RF signals in frequency bands utilized byvarious wireless communications systems, such as GSM and/or CDMA, forexample.

The multiband RF receiver 123 a may comprise suitable logic, circuitry,and/or code that may enable processing of received RF signals within oneor more distinct frequency ranges. The multiband RF receiver 123 a mayenable receiving RF signals in frequency bands utilized by variouswireless communication systems, such as WLAN, Bluetooth, GSM and/orCDMA, for example.

The digital baseband processor 129 may comprise suitable logic,circuitry, and/or code that may enable processing and/or handling ofdigital baseband signals. In this regard, the digital baseband processor129 may process or handle signals received from the multiband RFreceiver 123 a and/or signals to be transferred to the multiband RFtransmitter 123 b for transmission via a wireless communication medium.The digital baseband processor 129 may also provide control and/orfeedback information to the multiband RF receiver 123 a and to themultiband RF transmitter 123 b, based on information from the processedsignals. The digital baseband processor 129 may communicate informationand/or data from the processed signals to the processor 125 and/or tothe memory 127. Moreover, the digital baseband processor 129 may receiveinformation from the processor 125 and/or to the memory 127, which maybe processed and transferred to the multiband RF transmitter 123 b fortransmission via the wireless communication medium.

The processor 125 may comprise suitable logic, circuitry, and/or codethat may enable control and/or data processing operations for the mobileterminal 120. The processor 125 may be utilized to control at least aportion of the multiband RF receiver 123 a, the multiband RF transmitter123 b, the digital baseband processor 129, and/or the memory 127. Inthis regard, the processor 125 may generate at least one signal forcontrolling operations within the mobile terminal 120.

The memory 127 may comprise suitable logic, circuitry, and/or code thatmay enable storage of data and/or other information utilized by themobile terminal 120. For example, the memory 127 may be utilized forstoring processed data generated by the digital baseband processor 129and/or the processor 125. The memory 127 may also be utilized to storeinformation, such as configuration information, which may be utilized tocontrol the operation of at least one block in the mobile terminal 120.For example, the memory 127 may comprise information necessary toconfigure the multiband RF receiver 123 a to enable receiving RF signalsin the appropriate frequency band(s).

In an exemplary embodiment of a transmitting mobile terminal 120, themobile terminal 120 may comprise a multiband RF transmitter 123 b, adigital baseband processor 129, a processor 125, a memory 127, and aplurality of switches 124 a and 124 b, for example. In an exemplaryembodiment of a receiving mobile terminal 120, the mobile terminal 120may comprise a multiband RF receiver 123 a, a digital baseband processor129, a processor 125, a memory 127, and a plurality of switches 124 aand 124 b, for example.

FIG. 2 is a block diagram of an exemplary multiband RF transmitter, inaccordance with an embodiment of the invention. Referring to FIG. 2,there is shown a single chip RF transmitter 200, baluns 216 a and 216 b,and antennas 121 a and 121 b. The single chip RF transmitter 200 maycomprise a multiband RF transmitter 123 b, and a baseband processor 240.The multiband RF transmitter 123 b may comprise a transconductance stage250 and a plurality of gain stages 252 a and 252 b. The gain stage 252 amay comprise a power amplifier (PA) 214 a, a power amplifier driver(PAD) 212 a, an RF programmable gain amplifier (RFPGA) 210 a, atransmitter In-phase signal (I) mixer 208 a, a transmitterQuadrature-phase signal (Q) mixer 208 b, and a plurality of tunablecapacitors 223 a, 223 b and 223 c. The gain stage 252 b may comprise aPA 214 b, PAD 212 b, RFPGA 210 b, I mixer 208 c, Q mixer 208 d, and aplurality of tunable capacitors 223 d, 223 e and 223 f. Thetransconductance stage 250 may comprise, an I transconductance amplifier(gm) 206 a, a Q gm 206 b, an I low pass filter (LPF) 204 a, a Q LPF 204b, an I digital to analog converter (I DAC) 202 a, and a Q DAC 202 b.

The transconductance stage 250 may comprise suitable logic, circuitryand/or code that may enable generation of an analog quadrature signalbased on an input digital baseband signal. The analog quadrature signalmay comprise an I component signal and a Q component signal.

The gain stage 252 a may comprise suitable logic, circuitry and/or codethat may enable generation of an RF output signal based on an analoginput quadrature signal. The gain stage 252 a may generate the RF outputsignal by upconverting the analog input quadrature signal based on acarrier frequency selected from a frequency range, for example a 2.4 GHzfrequency range. The upconverted signal may be amplified through one ormore amplification stages and output as the RF output signal.

The gain stage 252 b may be substantially similar to the gain stage 252a. The gain stage 252 b may generate an RF output signal by upconvertingthe input quadrature signal based on a carrier frequency selected from adifferent frequency range from that selected in the gain stage 252 a,for example a 5 GHz frequency range.

The PA 214 a may comprise suitable logic, circuitry, and/or code thatmay enable amplification of input signals to generate a transmittedsignal of sufficient signal power (as measured by dBm, for example) fortransmission via a wireless communication medium. The PA 214 b may besubstantially similar to the PA 214 a.

The PAD 212 a may comprise suitable logic, circuitry, and/or code thatmay enable amplification of input signals to generate an amplifiedoutput signal. The PAD 212 a may be utilized in multistage amplifiersystems wherein the output of the PAD 212 a may be an input to asubsequent amplification stage. The PAD 212 b may be substantiallysimilar to the PAD 212 a.

The RFPGA 210 a may comprise suitable logic, circuitry, and/or code thatmay enable amplification of input signals to generate an amplifiedoutput signal, wherein the amount of amplification, as measured in dB,may be determined based on an input control signal. In variousembodiments of the invention, the input control signal may comprisebinary bits. The RFPGA 210 b may be substantially similar to the RFPGA210 a.

The transmitter I mixer 208 a may comprise suitable logic, circuitry,and/or code that may enable generation of an RF signal by upconversionof an input signal. The transmitter I mixer 208 a may utilize an inputlocal oscillator signal labeled as LO_(208a) to upconvert the inputsignal. The upconverted signal may be an RF signal. The transmitter Imixer 208 a may produce an RF signal for which the carrier frequency maybe equal to the frequency of the signal LO_(208a). The carrier frequencymay be selected from a frequency range, for example, a 2.4 GHz frequencyrange. The selected carrier frequency may be a center frequency for theRF signal generated by the transmitter I mixer 208 a.

The transmitter Q mixer 208 b may be substantially similar to thetransmitter I mixer 208 a. The frequency of the input local oscillatorsignal LO_(208b) may be equal to the frequency of the local oscillatorsignal LO_(208a), however, the local oscillator signal LO_(208b) mayhave a different phase in relation to the local oscillator signalLO_(208a). For example, the phase of the local oscillator signalLO_(208b) may be shifted 90° relative to the local oscillator signalLO_(208a).

The tunable capacitor 223 a may be coupled to a signal within the gainstage 252 a. Tuning of the tunable capacitor 223 a may enable a changingof the capacitance value of the tunable capacitor 223 a along with acorresponding modification of the center frequency of the coupledsignal. The tunable capacitors 223 b, 223 c, 223 d, 223 e and 223 f maybe substantially similar to the tunable capacitor 223 a.

The I gm 206 a may comprise suitable, logic, circuitry, and/or code thatmay enable generation of an output current, the amplitude of which maybe proportional to an amplitude of an input voltage to the I gm 206 a. Ameasure of proportionality between input voltage and output current maybe determined based on the transconductance parameter, gm_(I),associated with the I gm 206 a. The Q gm 206 b may be substantiallysimilar to the I gm 206 a. The transconductance parameter associatedwith the Q gm 206 b is gm_(Q).

The I LPF 204 a may comprise suitable logic, circuitry, and/or code thatmay enable selection of a cutoff frequency, wherein the LPF mayattenuate the amplitudes of input signal components for which thecorresponding frequency is higher than the cutoff frequency, while theamplitudes of input signal components for which the correspondingfrequency is less than the cutoff frequency may “pass,” or not beattenuated, or attenuated to a lesser degree than input signalcomponents at frequencies higher than the cutoff frequency. In variousembodiments of the invention, the I LPF 210 a may be implemented as apassive filter, such as one that utilizes resistor, capacitor, and/orinductor elements, or implemented as an active filter, such as one thatutilizes an operational amplifier. In an exemplary embodiment of theinvention, the I LPF 210 a may receive a differential input signal andoutput a differential output signal. The Q LPF 204 b may besubstantially similar to the I LPF 204 a.

The I DAC 202 a may comprise suitable logic, circuitry, and/or code thatmay enable conversion of an input digital signal to a correspondinganalog representation. The Q DAC 202 b may be substantially similar tothe I DAC 202 a.

The baseband processor 240 may comprise suitable logic, circuitry,and/or code that may enable processing of binary data contained withinan input digital baseband signal. The baseband processor 240 may performprocessing tasks, which correspond to one or more layers in anapplicable protocol reference model (PRM). For example, the basebandprocessor 240 may perform physical (PHY) layer processing, layer 1 (L1)processing, medium access control (MAC) layer processing, logical linkcontrol (LLC) layer processing, layer 2 (L2) processing, and/or higherlayer protocol processing based on input binary data. The processingtasks performed by the baseband processor 240 may be referred to asbeing within the digital domain. The baseband processor 240 may alsogenerate control signals based on the processing of the input binarydata.

In operation, the multiband RF transmitter 123 b may receive a digitalbaseband signal from the baseband processor 240. The digital basebandsignal may comprise an I component, I_(BB), and a Q component, Q_(BB).Signal I_(BB) may be input to the I DAC 202 a while the signal Q_(BB)may be input to the Q DAC 202 b.

The analog signals generated by the I DAC 202 a and the Q DAC 202 b maycomprise undesirable frequency components. The I LPF 204 a and Q LPF 204b may attenuate signal amplitudes associated with these undesirablefrequency components.

The I gm 206 a may receive the filtered signal from the I LPF 204 a andgenerate an I component signal, I_(Quad), of an analog quadrature signaloutput from the transconductance stage 250. The Q gm 206 b may receivethe filtered signal from the Q LPF 204 b and generate a Q componentsignal, Q_(Quad), of the analog quadrature signal output from thetransconductance stage 250.

The gain stage 252 a may receive the analog quadrature signal from thetransconductance stage 250. The baseband processor 240 may configure thetransmitter I mixer 208 a to select a carrier frequency for theLO_(208a) signal. The carrier frequency LO_(208a) may be selected from afrequency range, for example a 2.4 GHz frequency range. The LO_(208a)may be utilized to upconvert the I_(Quad) signal. The baseband processor240 may also configure the transmitter Q mixer 208 b to select a carrierfrequency for the LO_(208b) signal. The carrier frequency LO_(208b) maybe equal to the carrier frequency LO_(208a). The LO_(208b) may beutilized to upconvert the Q_(Quad) signal. The upconverted I_(Quad) andQ_(Quad) signals may be combined to form a composite analog RF signal,RF_(S1). The center frequency for the signal RF_(S1) may be based on thecarrier frequency LO_(208a), for example. The tunable capacitor 223 amay enable modification of the center frequency for the analog signalRF_(S1). The frequency modified signal RF_(S1)(LO_(208a)′) may bereceived by the RFPGA 210 a. The frequency modification, Δf₁, may berepresented as in the following equations:Δf ₁ =LO _(208a) ′−LO _(208a)  [1a]where:|Δf₁|≧0  [1b]

The baseband processor 240 may configure the RFPGA 210 a to amplify thesignal RF_(S1)(LO_(208a)′) by a gain level, as measured in dB, forexample. The RFPGA 210 a may generate an amplified signal RF_(S2). Thetunable capacitor 223 b may enable modification of the center frequencyfor the signal RF_(S2). The frequency modified signalRF_(S2)(LO_(208a)″) may be received by the PAD 212 a. The frequencymodification, Δf₂, may be represented as in the following equations:Δf ₂ =LO _(208a) ″−LO _(208a)′  [2a]where:|Δf₂|≧0  [2b]

The PAD 212 a may amplify the signal RF_(S2)(LO_(208a)″) by a gainlevel, as measured in dB, for example. The PAD 212 a may generate anamplified signal RF_(S3). The tunable capacitor 223 c may enablemodification of the center frequency for the signal RF_(S3). Thefrequency modified signal RF_(S3)(LO_(208a)′″) may be received by the PA214 a. The frequency modification, Δf₃, may be represented as in thefollowing equations:Δf ₃ =LO _(208a) ′″−LO _(208a)″  [3a]where:|Δf₃|≧0  [3b]The values Δf₁, Δf₂ and/or Δf₃ may be independently determined.

The PA 214 a may amplify the signal RF_(S3)(LO_(208a)′″) by a gainlevel, as measured in dB, for example. The PA 214 a may generate an RFoutput signal RF_(out1). The balun 216 a may enable energy from thesignal RF_(out1) to be transferred to the antenna 121 a from which thetransferred signal energy may be transmitted via a wirelesscommunication medium.

The operation of the gain stage 252 b may be substantially similar tothe operation of the gain stage 252 a. The gain stage 252 b may generatea signal RF_(out2). Within the gain stage 252 b, the I mixer 208 c and Qmixer 208 d may be configured to select a carrier frequency, representedby LO_(208c) and LO_(208d) respectively, which may be selected from afrequency range that is different from that utilized for selecting thecarrier frequency, LO_(208a) and LO_(208b). For example, the carrierfrequency for LO_(208c) and LO_(208d) may be selected from a 5 GHzfrequency range. The tunable capacitor 223 d may enable generation of amodification Δf₄, the value of which may be independent of the value ofΔf₁, Δf₂, and/or Δf₃, for example. The tunable capacitor 223 e mayenable generation of a modification Δf₅, the value of which may beindependent of the value of Δf₁, Δf₂, Δf₃ and/or Δf₄, for example. Thetunable capacitor 223 f may enable generation of a modification Δf₆, thevalue of which may be independent of the value of Δf₁, Δf₂, Δf₃, Δf₄and/or Δf₅, for example.

FIG. 3 is an exemplary block diagram illustrating a single chip RFtransmitter and receiver utilizing feedback of the RF output from thetransmitter through the receiver, in accordance with an embodiment ofthe invention. FIG. 3 shows a system utilizing a feedback path from theRF output to the baseband processor 240 via the multiband receiver 123a. The feedback may be utilize to enable the baseband processor 240 toestimate AM-AM and/or AM-PM distortion in one or more of the pluralityof RF output signals generated by the multiband RF transmitter 123 b.After estimating the AM-AM and/or AM-PM distortion, the basebandprocessor 240 may digitally predistort subsequent baseband signals tolinearize the PA circuits 214 a and/or 214 b within the multiband RFtransmitter 123 b.

Referring to FIG. 3, there is shown a single chip RF transceiver 300,baluns 216 a, 216 b, 222 a and 222 b, switches 124 a and 124 b, andantennas 121 a and 121 b. The antennas 121 a and 121 b, and switches 124a and 124 b are described in FIG. 1. The single chip RF transceiver 300may comprise a multiband RF receiver 123 a, a multiband RF transmitter123 b, a signal attenuation block 218, a feedback I mixer 220 a, afeedback Q mixer 220 b, a baseband processor 240 and a switch 235. Adetailed description of the multiband RF transmitter 123 b may be foundin FIG. 2. The multiband RF receiver 123 a may comprise a plurality ofRF low noise amplifiers (RFLNA) 224 a and 224 b, a plurality of receiverI mixers 226 a and 226 c, a plurality of receiver Q mixers 226 b and 226d, an I path selector switch 234 a, a Q path selector switch 234 b, aplurality of I high pass variable gain amplifiers (HPVGA) 228 a and 228c, a plurality of Q HPVGA 228 b and 226 d, a plurality of I LPFs 230 aand 230 c, a plurality of Q LPFs 230 b and 230 d, a plurality of Ianalog to digital converters (DAC) 232 a and 232 c, and a plurality of QDACs 232 b and 232 d.

In various embodiments of the invention, the baluns 216 a, 216 b, 222 aand 222 b may be integrated within the single chip RF transceiver 300.In various embodiments of the invention, electrical connections betweencomponents shown in FIG. 3 may be differential. In various otherembodiments of the invention, electrical connections between componentsshown in FIG. 3 may be single ended.

The switch 235 may enable one of a plurality of inputs to be selectivelycoupled to an output. In an exemplary embodiment of the invention, theswitch 235 may select from among 2 input signals, and couple theselected input signal to a single output. The I path selector switch 234a and the Q path selector switch 234 b may be substantially similar tothe switch 235.

The signal attenuation block 218 may comprise suitable logic, circuitry,and/or code that may enable generation of an output signal, theamplitude and/or power level of which may be based on an input signalafter insertion of a specified level of attenuation. In variousembodiments of the invention the attenuation level may be programmableover a range of attenuation levels. In an exemplary embodiment of theinvention, the range of attenuation levels may comprise −32 dB to −40dB, although various embodiments of the invention may not be limited tosuch a specific range.

The feedback I mixer 220 a may comprise suitable logic, circuitry,and/or code that may enable downconversion of an input signal. Thefeedback I mixer 220 a may utilize an input local oscillator signallabeled as LO_(220a) to downconvert the input signal. The feedback Qmixer 220 b may be substantially similar to the feedback I mixer 220 a.The feedback Q mixer 220 b may utilize an input local oscillator signallabeled LO_(220b) to downconvert the input signal. In an exemplaryembodiment of the invention, the phase of the local oscillator signalLO_(220b) may be shifted 90° relative to the local oscillator signalLO_(220a).

The RFLNA 224 a may comprise suitable logic, circuitry, and/or code thatmay enable amplification of weak signals (as measured by dBm, forexample), such as received from an antenna. The input signal to theRFLNA 224 a may be an RF signal received at the antenna 121 a, which iscommunicatively coupled to the RFLNA 224 a through the balun 222 a.

The receiver I mixer 226 a may be substantially similar to the feedbackI mixer 220 a. The receiver I mixer 226 a may utilize an input localoscillator signal labeled as LO_(226a) to downconvert the input signal.The frequency for the signal LO_(226a) may be selected from a frequencyrange, for example, a 2.4 GHz range.

The receiver Q mixer 226 b may be substantially similar to the feedbackQ mixer 220 b. The receiver Q mixer 226 b may utilize an input localoscillator signal labeled as LO_(226b) to downconvert the input signal.The frequency of the signal LO_(226b) may be equal to the frequency ofthe signal LO_(226a), however the phase of the signal LO_(226b) may beshifted 90° relative to the phase of the signal LO_(226a), for example.

The I HPVGA 228 a may comprise suitable logic, circuitry, and/or codethat may enable attenuation of input signals to generate an attenuatedoutput signal, wherein the amount of attenuation, as measured in dB forexample, may be determined based on an input control signal. In variousembodiments of the invention, the input control signal may comprisebinary bits. In various embodiments of the invention, the HPVGA 228 amay provide attenuation levels that range from 0 dB to −30 dB in 3 dBincrements. The Q HPVGA 228 b, I HPVGA 228 c and Q HPVGA 228 d may besubstantially similar to the I HPVGA 228 a.

The I LPF 230 a, Q LPF 230 b, I LPF 230 c and Q LPF 230 d may besubstantially similar to the I LPF 204 a.

The I ADC 232 a may comprise suitable logic, circuitry, and/or code thatmay enable conversion of an input analog signal to a correspondingdigital representation. The I ADC 232 a may receive an input analogsignal, which may be characterized by a signal amplitude. The I ADC 232a may quantize the analog signal by correlating ranges of analog signallevel values to corresponding numerical values. The I ADC 232 a maydetermine analog signal levels at distinct time instants by measuring,or integrating, the analog signal level of the input signal during atime interval referred to as δt. The time interval between measurements,or sampling interval, may be determined based on a sampling rate, whichis typically long in comparison to the integration time interval δt. TheQ ADC 232 b, I ADC 232 c and Q ADC 232 d may be substantially similar tothe I ADC 232 a.

In operation, the baseband processor 240 may configure the multiband RFreceiver 123 a and/or multiband RF transmitter 123 b for two distinctmodes of operation comprising a normal operating mode, and a calibrationmode. In the normal operating mode, the multiband RF transmitter 123 bmay transmit RF signals via the antennas 121 a and/or 121 b, while themultiband RF receiver 123 a may receive RF signals via the antennas 121a and/or 121 b. In the calibration mode, at least one of the pluralityof RF output signals, RF_(out1) and RF_(out2), from the multiband RFtransmitter 123 b may be selectively coupled via the switch 235 to aninput of the signal attenuation block 218. The selectively coupled RFoutput signal may be attenuated, downconverted into I and Q componentsignals, and inserted in the multiband RF receiver 123 a as feedbacksignals. Thus, the calibration mode may enable a closed feedback loopfrom the baseband processor 240, to the multiband RF transmitter 123 b,to a feedback point within the multiband RF receiver 123 a, and back tothe baseband processor 240.

As shown in FIG. 3, each selected RF output signal from the multiband RFtransmitter 123 b follows the feedback path through the I HPVGA 228 aand Q HPVGA 228 b, the I LPF 230 a and Q LPF 230 b, and the I ADC 232 aand Q ADC 232 b within the multiband RF receiver 123 a. In variousembodiments of the invention, each RF output signal may utilize aseparate feedback path through the multiband RF receiver 123 a to thebaseband processor 240, or may utilize dedicated circuitry external tothe multiband RF receiver 123 a to establish one or more feedback pathsfrom the RF output signals to the baseband processor 240.

Referring to FIG. 3, in a normal operating mode, the baseband processor240 may generate control signals that enable configuration of the I pathselector switch 234 a such that I path selector switch 234 a may beconfigured to select an input from the receiver I mixer 226 a. The Ipath selector switch 234 a may enable the output signal from thereceiver I mixer 226 a to be coupled to an input to the I HPVGA 228 a.The baseband processor 240 may also generate control signals that enableconfiguration of the Q path selector switch 234 b such that Q pathselector switch 234 b may be configured to select an input from thereceiver Q mixer 226 b. The Q path selector switch 234 b may enable theoutput signal from the receiver Q mixer 226 b to be coupled to an inputto the Q HPVGA 228 b.

In the normal operating mode, the multiband RF receiver 123 a mayreceive RF signals via the antenna 121. The RFLNA 224 may amplify thereceived RF signal, which may then be sent to the receiver I mixer 226a, Q mixer 226 b, I mixer 226 c and/or receiver Q mixer 226 d. Thereceiver I mixer 226 a may downconvert the amplified RF signal.Similarly, the receiver Q mixer 226 b may also downconvert the amplifiedRF signal. The I mixer 226 a and Q mixer 226 b may downconvert theamplified RF signal by utilizing a frequency selected from one of aplurality of frequency bands. For example, the frequency utilized by theI mixer 226 a and Q mixer 226 b may be selected from a 2.4 GHz frequencyband.

While the receiver I mixer 226 c and the receiver Q mixer 226 d may alsodownconvert the amplified RF signal. The I mixer 226 c and Q mixer 226 dmay downconvert the amplified RF signal by utilizing a frequencyselected from a distinct one of the plurality of frequency bands. Forexample, the frequency utilized by the I mixer 226 c and Q mixer 226 dmay be selected from a 5 GHz frequency band.

The baseband processor 240 may generate control signals that configurethe I HPVGA 228 a to amplify an I component portion of a receiveddownconverted signal. In an exemplary embodiment of the invention, the IHPVGA 228 a may amplify signal components for which the correspondingfrequency may be higher than baseband. Similarly, the baseband processor240 may generate control signals that configure the Q HPVGA 228 b toamplify a Q component portion of the received downconverted signal. TheI HPVGA 228 c and Q HPVGA 228 d may amplify I component and Q componentportions of a distinct downconverted signal.

The I LPF 230 a may filter the amplified signal received from the IHPVGA 228 a such that the output of the I LPF 230 a is an analogbaseband signal. The analog baseband signal may comprise a sequence ofsymbols. Similarly, the Q LPF 230 b may generate an analog basebandsignal. The I LPF 230 c and Q LPF 230 d may filter amplified signalsfrom the I HPVGA 228 c and Q HPVGA 228 d respectively.

The I ADC 232 a may convert an amplitude of a symbol in the analogbaseband signal received from the I LPF 230 a to a sequence of bits. Thesequence of bits may be contained in a digital baseband signal.Similarly, the Q ADC 232 b may convert an amplitude of a symbol in theanalog baseband signal received from the Q LPF 230 b to a sequence ofbits. The I ADC 232 c may convert an amplitude of a symbol in the analogbaseband signal received from the I LPF 230 c to a sequence of bits. TheQ ADC 232 d may convert an amplitude of a symbol in the analog basebandsignal received from the Q LPF 230 d to a sequence of bits. The basebandprocessor 240 may receive the sequence of bits from the I ADC 232 a andQ ADC 232 b, and/or from the I ADC 232 c and Q ADC 232 d, and performvarious processing tasks as set forth above.

In the calibration mode, the baseband processor 240 may generate controlsignals that may enable configuration of the I path selector switch 234a to select an input from the feedback I mixer 220 a. The I pathselector switch 234 a may enable the output signal from the feedback Imixer 220 a to be coupled to an input to the I HPVGA 228 a. The basebandprocessor 240 may also generate control signals that may enableconfiguration of the Q path selector switch 234 b to select an inputfrom the feedback Q mixer 220 b. The Q path selector switch 234 b mayenable the output signal from the feedback Q mixer 220 b to be coupledto an input to the Q HPVGA 228 b.

While the exemplary system illustrated in FIG. 3 shows 2 feedbackmixers, various embodiments of the invention may also utilize a singlefeedback mixer. In various embodiments of the invention that utilize asingle feedback mixer, the output from the single feedback mixer may beinput to the I HPVGA 228 a and Q HPVGA 228 b, for example.

Referring to FIG. 3, in the calibration mode, the baseband processor 240may generate control signals that may enable configuration of the switch235 to perform selection of an RF output signal from the plurality of RFoutput signals, RF_(out1) and RF_(out2), generated by the multiband RFtransmitter 123 b. The selected RF output signal may be coupled to theinput of the signal attenuation block 218 and utilized as a feedbacksignal. The signal attenuation block 218 may adjust the amplitude of theselected RF output signal to a level more suitable for input to thefeedback mixers 220 a and 220 b. The signal attenuation block 218 may beconfigured by the baseband processor 240 to apply a specifiedattenuation level to the input signal selected from the multiband RFtransmitter 123 b. The feedback I mixer 220 a may downconvert anattenuated RF signal to generate an I component signal. The feedback Qmixer 220 b may downconvert the attenuated RF signal to generate a Qcomponent signal. The I HPVGA 228 a may receive input signals from thefeedback I mixer 220 a, while the Q HPVGA 228 b may receive inputsignals from the feedback Q mixer 220 b.

The I LPF 230 a may filter the amplified signal received from the IHPVGA 228 a such that the output of the I LPF 230 a may be based on ananalog baseband component of the amplified signal received from the IHPVGA 228 a. Similarly, the Q LPF 230 b may generate an analog basebandsignal.

One possible limitation of the PA circuits 214 a and/or 214 b is thatthe output signal may become increasingly distorted as the output powerlevels from the PA circuits 214 a and/or 214 b increase. The distortionmay be detected through AM-AM distortion measurements, and/or AM-PMdistortion measurements.

In various embodiments of the invention, the calibration mode may enablethe baseband processor 240 to compensate for AM-AM distortion and/orAM-PM distortion. In one aspect of the invention, the calibration modemay enable the baseband processor 240 to send input digital basebandsignals I_(BB) and Q_(BB) to the multiband RF transmitter 123 b, fromwhich a plurality analog RF output signals may be generated. An analogRF output signal may be selected by the switch 235 and subsequentlyattenuated by the signal attenuation block 218, and downconverted by thefeedback I mixer 220 a and/or the feedback Q mixer 220 b. Thedownconverted signal generated by the feedback I mixer 220 a maycomprise an I signal component derived from the selected RF outputsignal, while the downconverted signal generated by the feedback Q mixer220 b may comprise a Q signal component. The downconverted signal fromthe feedback I mixer 220 a may be inserted into the multiband RFreceiver 123 a path as a feedback signal, I_(F), input to the I HPVGA228 a, while the downconverted signal from the feedback Q mixer 220 bmay be inserted into the multiband RF receiver 123 a path as a feedbacksignal, Q_(F), input to the Q HPVGA 228 b. The feedback signals, I_(F)and Q_(F), may be processed within the multiband RF receiver 123 a pathand received as digital baseband signals, I_(FB) and/or Q_(FB)respectively, at the baseband processor 240.

Based on the digital baseband signals I_(BB) and Q_(BB), and thefeedback digital baseband signals I_(FB) and Q_(FB), the basebandprocessor 240 may estimate AM-AM and/or AM-PM distortion in the RFoutput signals, RF_(out1) and/or RF_(out2), from the multiband RFtransmitter 123 b. Based on the AM-AM and/or AM-PM distortion estimates,the baseband processor 240 may predistort subsequent digital basebandsignals I_(BB) and/or Q_(BB). By predistorting the digital basebandsignals I_(BB) and/or Q_(BB), the baseband processor 240 may linearizethe PA circuits 214 a and/or 214 b in the multiband RF transmitter 123b. By linearizing the PA circuits 214 a and/or 214 b, the analog RFoutput signals, RF_(out1) and/or RF_(out2), generated by the PA circuits214 a and 214 b may change linearly in response to changes in theundistorted digital baseband signals I_(BB) and Q_(BB) from the basebandprocessor 240.

In various embodiments of the invention, digital predistortion may beutilized to linearize the PA circuits 214 a and/or 214 b, which maythereby enable the PA circuits 214 a and/or 214 b to transmit signals athigher average output power levels while still complying with relevantEVM specifications, for example. Further details describing exemplarymethods of calibration for digital predistortion are disclosed in U.S.patent application Ser. No. 11/618,876 filed Dec. 31, 2006, which ishereby incorporated herein in its entirety.

FIG. 4 is a flowchart illustrating exemplary steps for generating aplurality of output RF signals in a multiband RF transmitter, inaccordance with an embodiment of the invention. Referring to FIG. 4, instep 402, the baseband processor 240 may generate a digital basebandsignal. In step 404, the transconductance stage 250 may generate ananalog quadrature signal based on the digital baseband signal. In step406, a processor 125 may select a plurality of carrier frequencies. Eachcarrier frequency may be selected from a distinct frequency band. Thenumber of selected carrier frequencies may be equal to the number ofgain stages 252 a and 252 b. In step 408, each gain stage 252 a and 252b may generate an analog RF output signal. Each analog RF output signalmay be generated by utilizing a distinct carrier frequency from theplurality of carrier frequencies selected in step 406.

Various aspect of a system for a linearized transmitter including apower amplifier may include at least one transconductance amplifier 206a that enables generation of a single analog quadrature signal.Transmitter mixers 208 a, 208 b, 208 c and 208 d may enable generationof a plurality of upconverted RF signals in a corresponding plurality ofRF processing chains based on the generated single analog quadraturesignal. In various embodiments of the invention, a gain stage, forexample gain stage 250, may also be referred to as an RF processingchain. Power amplifier circuit 214 a and 214 b may enable generation ofa corresponding plurality of RF output signals within a wirelesscommunication system 120 based on the generated plurality of upconvertedRF signals.

The single analog quadrature signal may comprise an in-phase componentand a quadrature-phase component. The transmitter mixers 208 a, 208 b,208 c and 208 d may enable generation of the plurality of each of theplurality of upconverted RF signals based on the generated single analogquadrature signal and a selected center frequency. The selected centerfrequency may be selected from a frequency range. The frequency rangemay be distinct from a previous frequency range and/or a subsequentfrequency range utilized for generating a previous one of the pluralityof upconverted RF signals and/or a subsequent one of the plurality ofupconverted RF signals. Tunable capacitors 223 a and 223 d may enableindependent adjustment of a center frequency for each of the generatedplurality of upconverted RF signals. The independent adjustmentincreases, decreases or leaves unchanged, the center frequency for eachof the generated plurality of upconverted RF signals.

One or more sets of RFPGA circuits 210 a and 210 b may enable generationof a first stage amplified signal based on each of the generated aplurality of first stage amplified signals each based on a correspondingone of the generated plurality of upconverted RF signals following theindependent adjustment of the center frequency. Tunable capacitors 223 band 223 e may enable independent adjustment of a center frequency foreach of the plurality of first stage amplified signals. The independentadjustment increases, decreases or leaves unchanged, the centerfrequency for each of the plurality of first stage amplified signals.

One or more sets of PAD circuits 212 a and 212 b may enable generationof one or more pluralities of subsequent stage amplified signals basedon the generated plurality of first stage amplified signals followingthe independent adjustment of the center frequency for each of theplurality of generated first stage amplified signals. At least one setof tunable capacitors 223 c and 223 f may enable independent adjustmentof a center frequency for each of the generated one or more pluralitiesof subsequent stage amplified signals. The independent adjustmentincreases, decreases or leaves unchanged, the center frequency for eachof the generated one or more pluralities of subsequent stage amplifiedsignals.

PA circuits 214 a and 214 b may enable generation of each of thecorresponding plurality of RF signals based on a corresponding last ofthe generated one or more pluralities of subsequent stage amplifiedsignals following independent adjustment of the center frequency foreach of the generated one or more pluralities of subsequent stageamplified signals. The PA circuits 214 a and 214 b may enabletransmission of at least a portion of the generated correspondingplurality of RF signals via a wireless communication medium.

A switch 235 may enable selection of one or the corresponding pluralityof generated RF output signals. Feedback mixer circuits 220 a and 220 bmay enable generation of one or more feedback signals by performing afrequency downconversion operation on the selected one of thecorresponding plurality of generated RF output signals. An I pathselector switch 234 a and/or Q path selector switch 234 b may enableinsertion of the generated feedback signals at corresponding insertionspoint(s) in a receiver circuit 123 a. Each insertion point may bebetween a corresponding receiver mixer circuit 226 a, 226 b, 226 cand/or 226 d, and a corresponding one or more circuits, 228 a, 230 a and232 a for example, that generates a based band signal corresponding toone of the generated feedback signals. Transconductance amplifiers 206 aand 206 b may enable generation of the single quadrature signal in asingle transconductance stage circuit 250.

Accordingly, the present invention may be realized in hardware,software, or a combination of hardware and software. The presentinvention may be realized in a centralized fashion in at least onecomputer system, or in a distributed fashion where different elementsare spread across several interconnected computer systems. Any kind ofcomputer system or other apparatus adapted for carrying out the methodsdescribed herein is suited. A typical combination of hardware andsoftware may be a general-purpose computer system with a computerprogram that, when being loaded and executed, controls the computersystem such that it carries out the methods described herein.

The present invention may also be embedded in a computer programproduct, which comprises all the features enabling the implementation ofthe methods described herein, and which when loaded in a computer systemis able to carry out these methods. Computer program in the presentcontext means any expression, in any language, code or notation, of aset of instructions intended to cause a system having an informationprocessing capability to perform a particular function either directlyor after either or both of the following: a) conversion to anotherlanguage, code or notation; b) reproduction in a different materialform.

While the present invention has been described with reference to certainembodiments, it will be understood by those skilled in the art thatvarious changes may be made and equivalents may be substituted withoutdeparting from the scope of the present invention. In addition, manymodifications may be made to adapt a particular situation or material tothe teachings of the present invention without departing from its scope.Therefore, it is intended that the present invention not be limited tothe particular embodiment disclosed, but that the present invention willinclude all embodiments falling within the scope of the appended claims.

1. A method for generating signals in a transmitter circuit within awireless communications system, the method comprising: generating asingle analog quadrature signal; generating a plurality of upconvertedRF signals in a corresponding plurality of RF processing chains based onsaid generated single analog quadrature signal; and generating, within awireless communication system, a corresponding plurality of RF outputsignals based on said generated plurality of upconverted RF signals. 2.The method according to claim 1, wherein said signal analog quadraturesignal comprises an in-phase component and a quadrature-phase component.3. The method according to claim 1, comprising generating said each ofsaid plurality of upconverted RF signals based on said generated singleanalog quadrature signal and a selected center frequency.
 4. The methodaccording to claim 3, wherein said selected center frequency is selectedfrom a frequency range.
 5. The method according to claim 4, wherein saidfrequency range is distinct from one or both of: a previous frequencyrange and a subsequent frequency range, utilized for generating one orboth of: a previous one of and a subsequent one of, said plurality ofupconverted RF signals.
 6. The method according to claim 1, comprisingindependently adjusting a center frequency for each of said generatedplurality of upconverted RF signals.
 7. The method according to claim 6,wherein said independent adjusting increases, decreases or leavesunchanged, said center frequency for said each of said generatedplurality of upconverted RF signals.
 8. The method according to claim 6,comprising generating a plurality of first stage amplified signals eachbased on a corresponding said each of said generated plurality ofupconverted RF signals following said independent adjusting said centerfrequency for said each of said generated plurality of upconverted RFsignals.
 9. The method according to claim 8, comprising independentlyadjusting a center frequency for each of said generated plurality offirst stage amplified signals.
 10. The method according to claim 9,wherein said independent adjusting increases, decreases or leavesunchanged, said center frequency for said each of said generatedplurality of first stage amplified signals.
 11. The method according toclaim 9, comprising generating at least one plurality of subsequentstage amplified signals based on said generated plurality of first stageamplified signals following said independent adjusting said centerfrequency for said each of said generated plurality of first stageamplified signals.
 12. The method according to claim 11, comprisingindependently adjusting a center frequency for each individual signal insaid generated at least one plurality of subsequent stage amplifiedsignals.
 13. The method according to claim 12, wherein said independentadjusting increases, decreases or leaves unchanged, said centerfrequency for said each individual signal in said generated at least oneplurality of subsequent stage amplified signals.
 14. The methodaccording to claim 12, comprising generating each of said generatedcorresponding plurality of RF signals based on a corresponding last ofsaid generated at least one plurality of subsequent stage amplifiedsignals following said independent adjusting said center frequency forsaid each individual signal in said generated at least one plurality ofsubsequent stage amplified signals.
 15. The method according to claim14, comprising transmitting at least a portion of said each of saidgenerated corresponding plurality of RF signals via a wirelesscommunication medium.
 16. The method according to claim 1, comprising:selecting one of said corresponding plurality of generated RF outputsignals; generating one or more feedback signals by performing afrequency downconversion operation on said selected one of saidcorresponding plurality of generated RF output signals within acorresponding one or more feedback mixer circuits; and inserting saidgenerated one or more feedback signals at a corresponding one or moreinsertion points in a receiver circuit, wherein each of saidcorresponding one or more insertion points is between a correspondingreceiver mixer circuit and a corresponding one or more circuits thatgenerates a baseband signal based on a corresponding one of saidgenerated one or more feedback signals.
 17. The method according toclaim 1, comprising generating said single analog quadrature signal in asingle transconductance stage circuit.
 18. A system for generatingsignals in a transmitter circuit within a wireless communicationssystem, the system comprising: one or more circuits, comprising at leastone transconductance amplifier, that enable generation of a singleanalog quadrature signal; said one or more circuits, comprising at leasta transmitter mixer, enable generation of a plurality of upconverted RFsignals in a corresponding plurality of RF processing chains based onsaid generated single analog quadrature signal; and said one or morecircuits, comprising at least one power amplifier circuit, enablegeneration, within a wireless communication system, of a correspondingplurality of RF output signals based on said generated plurality ofupconverted RF signals.
 19. The system according to claim 18, whereinsaid single analog quadrature signal comprises an in-phase component anda quadrature-phase component.
 20. The system according to claim 18,wherein said one or more circuits comprise at least said transmittermixer and enable generation of said each of said plurality ofupconverted RF signals based on said generated single analog quadraturesignal and a selected center frequency.
 21. The system according toclaim 20, wherein said selected center frequency is selected from afrequency range.
 22. The system according to claim 21, wherein saidfrequency range is distinct from one or both of: a previous frequencyrange and a subsequent frequency range, utilized for generating one orboth of: a previous one of and a subsequent one of, said plurality ofupconverted RF signals.
 23. The system according to claim 18, whereinsaid one or more circuits comprise at least a first tunable capacitorand enable independent adjustment of a center frequency for each of saidgenerated plurality of upconverted RF signals.
 24. The system accordingto claim 23, wherein said independent adjustment increases, decreases orleaves unchanged, said center frequency for said each of said generatedplurality of upconverted RF signals.
 25. The system according to claim23, wherein said one or more circuits comprise at least one RFprogrammable gain amplifier circuit, at least one power amplifier drivercircuit and/or said at least one power amplifier circuit and enablegeneration of a plurality of first stage amplified signals each based ona corresponding said each of said generated plurality of upconverted RFsignals following said independent adjustment of said center frequencyfor each of said generated plurality of upconverted RF signals.
 26. Thesystem according to claim 25, wherein said one or more circuits compriseat least a second tunable capacitor and enable independent adjustment ofa center frequency for each individual signal in said generatedplurality of first stage amplified signals.
 27. The system according toclaim 26, wherein said independent adjustment increases, decreases orleaves unchanged, said center frequency for said each of said generatedplurality of first stage amplified signals.
 28. The system according toclaim 26, wherein said one or more circuits comprise said at least oneRF programmable gain amplifier circuit, said at least one poweramplifier driver circuit and/or said at least one power amplifiercircuit and enable generation of at least one plurality of subsequentstage amplified signals based on said generated plurality of first stageamplified signals following said independent adjustment of said centerfrequency for said each of said generated plurality of first stageamplified signals.
 29. The system according to claim 28, wherein saidone or more circuits comprise at least one subsequent tunable capacitorand enable independent adjustment of a center frequency for eachindividual signal in said generated at least one plurality of subsequentstage amplified signals.
 30. The system according to claim 29, whereinsaid independent adjustment increases, decreases or leaves unchanged,said center frequency for said each generated at least one plurality ofsubsequent stage amplified signals.
 31. The system according to claim29, wherein said one or more circuits comprise said power amplifiercircuit and enable generation of each of said generated correspondingplurality of RF signals based on a corresponding last of said generatedat least one subsequent stage amplified signal following saidindependent adjustment of said center frequency for each individualsignal in said generated at least one plurality of subsequent stageamplified signals.
 32. The system according to claim 31, wherein saidone or more circuits comprise said at least one power amplifier circuitand enable transmission of at least a portion of said each of saidgenerated corresponding plurality of RF signals via a wirelesscommunication medium.
 33. The system according to claim 18, comprising:one or more circuits, comprising at least a switch, that enableselection of one of said corresponding plurality of generated RF outputsignals; said one or more circuits, comprising at least a correspondingone or more feedback mixer circuits, enable generation of one or morefeedback signals by performing a frequency downconversion operation onsaid selected one of said corresponding plurality of generated RF outputsignals; and said one or more circuits, comprising at least one pathselector switch, enable insertion of said generated one or more feedbacksignals at a corresponding one or more insertion points in a receivercircuit, wherein each of said corresponding one or more insertion pointsis between a corresponding receiver mixer circuit and a correspondingone or more circuits that generates a baseband signal based on acorresponding one of said generated one or more feedback signals. 34.The system according to claim 18, wherein said one or more circuitscomprise at least said at least one transconductance amplifier andenable generation of said single analog quadrature signal in a singletransconductance stage circuit.